The regulatory requirements Radio Technical Commission for Aeronautics (RTCA), Inc. (RTCA/DO-260B) for automatic dependent surveillance-broadcast (ADS-B) OUT operation require the following:
“The time of applicability to which the encoded latitude and longitude in an Airborne or Surface Position Messages are computed shall be within 100 milliseconds of the time of transmission.”
“The position register shall be reloaded with position data at intervals that are no more than 200 milliseconds apart. The position being loaded into the Register shall have a time of applicability that is never more than 200 milliseconds different from any time during which the Register holds that data.”
One issue is that the processing for extrapolating global positioning system (GPS) position in the polar region is extensive and taxing for microcontrollers or processors without floating point capability.